The invention relates to biocontrol agents for suppressing weed growth. More specifically the present invention relates to bacterial biocontrol agents for suppression of weed growth.
Chickweed (Stellaria media) is one of the most important weeds in Canada. It is a vigorous competitor for space and nutrients; an aesthetic problem in agricultural crops, market gardens, and urban centers; and listed as a noxious weed in the Noxious Weeds Act of Alberta and Manitoba (Mann et al., 1950; Terkington et al., 1980).
Chickweed is distributed across all Canadian provinces. It is found from Vancouver Island to Newfoundland, and from the United States border to the Mackenzie delta at 69 N (Terkington et al., 1980). Previous data showed that chickweed is more common in B.C. and eastern Canada than in the prairies, however, its populations in the prairie provinces of Canada have been dramatically increasing over the past 10 years. Overall, the relative abundance of chickweed over these years rose by 4, 6, and 17 rankings in Alberta, Saskatchewan and Manitoba, respectively (Thomas et al., 1998). Presently, chickweed is the most abundant weed species in Alberta, followed by wild oats (Thomas et al., 1997).
The main control method is the use of chemical herbicides that belong mainly to Groups 2 and 4. However, herbicide resistance in chickweed to Group-2 herbicides in Canada and Group-4 herbicides in Europe has been reported (Devine et al., 1991; Hall and Devine, 1990; Lutman & Heath, 1990; O'Donovan et al., 1994). Herbicide resistance development in chickweed substantially limits herbicide choices for its control in most crops and other non-agricultural lands such as home gardens and lawns. This situation provides an opportunity to develop “biological herbicide” or “bioherbicide” or “microbial herbicides” for chickweed control.